The "predators" in question are not "big game" in the way typically thought. They're a kind of pack-based omnivores. They do eat meat, if they can hunt it down. They're quasi-mammalian quadrapeds, which make strike the players as monkey-like in their movement and behavior, though they are not furred but scaled and have elongated heads reminscent of the native wildlife. They have what appears to be six-fingered feet and hands in a 3-digits opposed arrangement with three fingers and three "thumbs" and their "hands" are identical to their feet (this is a common body arrangement on the world). They spend most of their time on all fours, but can spend limited amounts of time using their "hands" in a bipedal stance. Like many monkeys, to move fast they use all fours and cannot move quickly in a purely bipedal stance.
Normally, they're relatively peaceful, living up in the cloud-forests and so on, whereas the human population lives in the valleys and plains; the two species rarely interact.
Maybe once every decade or so, however, due to population pressures or a few years without rain, packs of these omnivores are driven down off of the mountains towards where people live. That's when the problems start. They're predators in that go into the local fields and gather crops and "hunt" livestock.
The problem is that they're also amazing mimics. It appears that they can understand somewhat abstract cause-and-effect: Like they can understand that "bang stick" the human is carrying has some ability to harm you if it is pointed at you, even from afar. They are "masters" of camouflage (not really - just not totally inept at it like most humans) and are keen observers. They also learn quickly. They can learn how to open doors, operate code keypads if they see someone punching in the numbers in sequence. They can also learn to operate firearms. They "language" is limited to simple social sounds, and while they can teach each other how to do things, they can only learn by observation by another pack member and they don't have "classroom teaching" - the mimics watch others doing the same action for its intended end other than just teaching (most of the time - mothers will make more of an effort to teach their children). They use simple tools normally, but are known to have a long-term memory of "favorite" tools such as clubs and will store them in a particular location and fetch them to use it and return it when they're done.
Nevertheless, they are quite dangerous as farmer responses tend to be try and cull them like other animals. Eventually, the creatures (who live in packs of anywhere from about 15 - 30 individuals, but "megapacks" or "coalitions" are known to form temporarily with 100 or more members) take losses but also start to learn out how use how to use rifles and so on by watching their hunters. Eventually the farmers get mobbed, the creatures become armed, and things start getting dangerous. The mimicry can get eeriely knowledgeable, but has limits - a mimic watching a human use an assault rifle might learn the rifle's basic operation and even how to reload magazines from an ammo vest. However, it will not understand how to reload the magazine from loose rounds (because it's never seen it done and most individuals don't appear sufficiently adept at abstract thinking to understand the idea of having to reload the reloader).
The creatures don't have writing, complex language, or social organization more complex than a pack so are not considered sentient by local authorities. However, due to their intelligence, the local world does not permit indiscriminate solutions like poisoning or introducing tailored diseases to wipe them out. Local farmers tend to have a superstitious fear of them with some agitating the government to allow them to wipe them out using viruses or something, while other farmers oppose the idea.
Because of their mimic-like nature, however, the local government does require that all members of a given pack are wiped out once even one member has learned how to do things like operate firearms; this has proved successful in the past by destroying the knowledge before it spreads.
Possible Complications
1. The players are not the first group to have been hired to solve this problem for the locals. The first group, which became the hunted, were lower-tech mercenaries (likely veterans from a local balkanized world that has wars). The mimics in question can operate throw hand grenades, and even have a few crew-served weapons (such as machine guns or RPG-type weapons - the creatures abstract thinking apparently does not extend to operation of weapons like mortars).
1-1. Alternatively, the the mercs were very high-tech but few in number and were using rugged "survival" laser weapons that can recharge using solar power and water. The mimics have taken to simply "storing" the weapon in shallow pools or streams and so have essentially an unlimited supply of ammunition.
2. A local biologist notes that the creatures have a chromosome system for reproduction and have 23 pairs of chromosomes, the same number as humans. The biologist believes that the mimics, despite their alien appearance are probably descended from earthlife. Players with skills in biology (or related disciplines) might note how unlikely it is for earthlife to have 23 pairs of chromosomes...
2-1. The mimics are not just clubbing mercs and farmers over the head. They're deliberately being armed by some group.
2-1-1. The group that is arming them is a local free trader or corporate officer who wants to evaluate the creatures suitability for use as servants or possibly even mercenary cannon fodder. There's a strong religious-level local taboo against this, which is why they're operating like this. In this variation, players should note that the world's colonists are almost purely of Solomani descent (though they don't make a big deal about it). The natives point out the world was settled during the Rule of Man by Solomani settlers. However, the players may happen upon badly eroded ruins in places like caves in the highlands that clearly have the hallmarks of being Vilani construction. During the RoM, the Solomani came to the world to run the government after the collapse of the Ziru Sirkaa. However, they never got along with the Vilani settlers who were already long-established. As the Second Imperium collapsed, the Solomani realized that without the backing of the Solomani military, the natives would likely rise up and kill them all. The Solomani, therefore, developed a retrovirus that would prey upon the unique genetic markers of the Vilani...one that would turn their children into beasts that look a lot like local wildlife. Creatures without a language but could be taught various tasks to be useful to the colonists. However, the resulting species was not so tractable as the Solomani hoped. The guilt over what happened was quickly subsumed by keeping it a secret from future generations with only few "local traditions" such as it being taboo to kill the creatures except in self-defense and no "genocidal" solutions.
2-1-2. As 2-1-1, but the creatures are being armed by Racheleans. A cell of Racheleans have also figured out the truth. Fortunately, they haven't figured out the PR value this would have in damaging Solomani-Vilani relations and instead acting in pure rage as to what happened. If world gets out about this, it certainly will cause a rise in hate crimes in the local worlds, though news of it will not spread beyond the subsector except in the form of legends which will tend to become unbelieved urban myths. Strange things, those X-Boats.
2-1-2-1. As above but the Imperium knows the truth of what happened as they figured it out (it's not hard if you have the clues) decades or even centuries ago. However, the Imperium doesn't see the point in bringing up ancient history, no matter vile; the criminals are long dead, as are their children for many generations. It'd just damage Solomani-Vilani relations due to the human tendency to "contemporize" things, no matter how distant in the past. The players may run into an Agent of the Imperium who explains this and how the status quo must be upheld, no matter how bad, because it really is the best solution for a situation without any palatable solutions. Players who agree to play along will have their own memories of the incident selectively wiped by a trained Psion but in return will receive a bribe ("Hm, you know, 1,000,000 Cr for a mission to cull local wildlife is pretty good..."). Those who refuse ... well ... now they're on the bad side of someone with an Imperial Warrant.
